Method of manufacturing circuit structure

ABSTRACT

Provided is a circuit structure including a substrate, a pad, a dielectric layer, a conductive layer, an adhesion layer, and a conductive bump. The pad is disposed on the substrate. The dielectric layer is disposed on the substrate and exposes a portion of the pad. The conductive layer contacts the pad and extends from the pad to cover a top surface of the dielectric layer. The adhesion layer is disposed between the dielectric layer and the conductive layer. The conductive bump extends in an upward manner from a top surface of the conductive layer. The conductive bump and the conductive layer are integrally formed. A method of manufacturing the circuit structure is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of and claims the priority benefit ofU.S. application Ser. No. 16/264,696, filed on Feb. 1, 2019, nowpending. The entirety of the above-mentioned patent application ishereby incorporated by reference herein and made a part of thisspecification.

BACKGROUND Technical Field

The disclosure relates to a semiconductor structure and a method ofmanufacturing the same, and more particularly to a circuit structure anda method of manufacturing the same.

Description of Related Art

Recently, the continuous increase in the integration of variouselectronic components (e.g., transistors, diodes, resistors, capacitors,and so on) leads to the rapid growth of the semiconductor industry. Theincrease in the integration mostly results from the continuous reductionof the minimum feature size, so that more components can be integratedinto a given area.

Compared to the convention package structure, these electroniccomponents with smaller size occupy smaller area and thus require asmaller package structure. For instance, a semiconductor chip or die hasan increasing number of input/output (I/O) solder pads, and aredistribution layer (RDL) can redistribute the original I/O solder padsof the semiconductor chip or die to be located around the semiconductorchip or die, so as to increase the number of I/O solder pads.

However, in the conventional wafer level packaging process, the RDLstructure and a copper pillar bump have a multi-layer structure formedby repeatedly performing sputtering, plating, lithography, etching, andother manufacturing processes. In addition to the cumbersome steps, theyield loss, material waste, and diversification of the manufacturingmachine in the plural manufacturing processes lead to the increase inthe manufacturing costs. Besides, the adhesion issue may occur in layersof the multi-layer structure, and intermetallic compounds (IMCs) arelikely to be generated among different metal materials. Hence, theinterface between the conventional RDL structure and the copper pillarbump often suffers from peeling and being crack during the reliabilitytest.

SUMMARY

The disclosure provides a circuit structure including a substrate, apad, a dielectric layer, a conductive layer, an adhesion layer, and aconductive bump. The pad is disposed on the substrate. The dielectriclayer is disposed on the substrate and exposes a portion of the pad. Theconductive layer contacts the pad and extends from the pad to cover atop surface of the dielectric layer. The adhesion layer is disposedbetween the dielectric layer and the conductive layer. The conductivebump extends in an upward manner from a top surface of the conductivelayer. The conductive bump and the conductive layer are integrallyformed.

The disclosure provides a method of manufacturing a circuit structure. Apad is formed on a substrate. A dielectric layer is formed on thesubstrate. The dielectric layer has an opening exposing a portion of thepad. An adhesion layer is formed on the dielectric layer. The adhesionlayer covers a sidewall of the opening and extends to cover a topsurface of the dielectric layer. A circuit layer is formed by using afirst three-dimensional (3D) printing technology. The circuit layerincludes a conductive layer and a conductive bump. The conductive layercontacts the pad and extends along a first direction from the pad tocover a top surface of the adhesion layer. The conductive bump extendsalong a second direction from a first top surface of the conductivelayer on the adhesion layer. The first direction is different from thesecond direction. A passivation layer is formed on the circuit layer.The passivation layer covers a second top surface of the conductivelayer and covers a portion of a sidewall of the conductive bump. Asolder layer is formed on the conductive bump.

In view of the above, the 3D printing technology is applied in thedisclosure to form the circuit layer (including the conductive layer andthe conductive bump), so that the conductive layer and the conductivebump are integrally formed. Namely, the conductive layer and theconductive bump are made of the same material in the same manufacturingstep, so as to prevent the adhesion and IMC issues between differentmaterials. Thereby, the structural strength between the conductive layerand the conductive bump in the circuit structure can be significantlyimproved according to one or more embodiments of the disclosure, andproduct reliability can be further improved. In addition, the method ofmanufacturing the circuit structure provided herein has simplemanufacturing steps, thus enhancing commercial competitiveness of theproduct.

To make the above features and advantages described in one or more ofthe embodiments provided in the disclosure more comprehensible, severalembodiments accompanied with drawings are described in detail asfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments of thedisclosure and, together with the description, serve to explain theprinciples described herein.

FIG. 1A to FIG. 1E are schematic cross-sectional views illustrating amanufacturing process of a circuit structure according to an embodimentof the disclosure.

FIG. 2 is an enlarged cross-sectional view illustrating a portion of thecircuit structure depicted in FIG. 1C.

DESCRIPTION OF THE EMBODIMENTS

The invention will be described in a more comprehensive manner withreference to the drawings of the embodiments. This invention, however,may be embodied in many different forms and should not be construed aslimited to the embodiments set forth herein. The thickness of layers andregions in the drawings may be exaggerated for clarity. The same orsimilar reference numbers used in the embodiments represent the same orsimilar devices. Accordingly, no further description thereof is providedhereinafter.

FIG. 1A to FIG. 1E are schematic cross-sectional views illustrating amanufacturing process of a circuit structure according to an embodimentof the disclosure. FIG. 2 is an enlarged cross-sectional viewillustrating a portion of the circuit structure depicted in FIG. 1C.Here, the circuit structure provided in the present embodiment may be aredistribution layer (RDL) structure, which should however not beconstrued as a limitation in the disclosure. In other embodiments, thecircuit structure may also be an interconnect structure in aback-end-of-line (BEOL) process, a circuit structure in a circuit board,or any other similar structure.

With reference to FIG. 1A, a method of manufacturing a circuit structureincludes following steps. Firstly, a substrate 100 is provided.According to an embodiment, the substrate 100 includes a semiconductormaterial. In particular, the substrate 100 may be made of at least onesemiconductor material selected from the group consisting of Si, Ge,SiGe, GaP, GaAs, SiC, SiGeC, InAs, and InP. In the present embodiment,the substrate 100 may be, for example, a silicon substrate. Besides, thesubstrate 100 may also include a silicon on insulator (SOI) substrate.In FIG. 1A, no device is disposed in the substrate 100; however, thesubstrate 100 provided in the present embodiment may be equipped withactive devices (e.g., a transistor, a diode, and so on), passive devices(e.g., a capacitor, an inductor, a resistor, and so on), or acombination thereof. In other embodiments, the substrate 100 may beequipped with logic devices, memory devices, or a combination thereof.

A pad 102 is then formed on the substrate 100. According to anembodiment, the material of the pad 102 includes a metallic material,such as copper, aluminum, gold, silver, nickel, palladium, or acombination thereof. A method of forming the pad 102 includes physicalvapor deposition (PVD), plating, or a combination thereof. Only one pad102 is illustrated in FIG. 1A, however, the invention is not limitedthereto. In other embodiments, the number of the pad 102 may be adjustedaccording to actual demands. According to an embodiment, the pad 102 maybe electrically connected to devices (not shown) in the substrate 100.

After that, a dielectric layer 104 is formed on the substrate 100. Thedielectric layer 104 covers a sidewall of the pad 102 and one portion ofa top surface of the pad 102. As shown in FIG. 1A, the dielectric layer104 has an opening 105. The opening 105 exposes another portion of a topsurface 102 t of the pad 102. According to an embodiment, the materialof the dielectric layer 104 includes a dielectric material, such assilicon oxide, silicon nitride, silicon oxynitride, polyimide, or acombination thereof. A method of forming the dielectric layer 104includes PVD, chemical vapor deposition (CVD), or a combination thereof.

With reference to FIG. 1B, the adhesion layer 106 is formed by using a3D printing technology. According to an embodiment, the 3D printingtechnology includes an ink jet printing process, an aerosol jet printingprocess, or a combination thereof. The aerosol jet printing process istaken as an example, wherein an aerosol jet deposition head is appliedto form an annularly propagating jet constituted by an outer sheath flowand an inner aerosol-laden carrier flow. During the aerosol jet printingprocess, an aerosol stream of the to-be-deposited materials isconcentrated and deposited onto a surface to be formed. Said step may bereferred to as maskless mesoscale material deposition (M3D), i.e., thedeposition step can be performed without using any mask.

In the present embodiment, as shown in FIG. 1B, the nozzle 202 of the 3Dprinting apparatus is applied to eject an insulation ink 204 onto thedielectric layer 104 along a first direction D1. According to anembodiment, the insulation ink 204 includes an insulation material and asolvent. For instance, the insulation material may be polyimide,polyurethane (PU), or the like. The solvent may beN-Methyl-2-pyrrolidone (NMP), propylene glycol monomethyl ether (PGME),ethylene glycol, or the like. After a curing step is performed, theinsulation ink 204 is cured and becomes the adhesion layer 106. In analternative embodiment, the curing step includes a heating step or anirradiating step for volatilizing the solvent in the insulation ink 204and curing the insulation ink 204. In this case, as shown in FIG. 1B,the adhesion layer 106 covers a sidewall 105 s of the opening 105 andextends to cover a top surface 104 t of the dielectric layer 104.According to an embodiment, the adhesion layer 106 includes aninsulation compound, such as polyimide, PU, SU-8, an adhesive, or acombination thereof. In the present embodiment, the adhesion layer 106can increase the adhesion between the dielectric layer 104 and thesubsequently formed conductive layer 112 (as shown in FIG. 1C). In thepresent embodiment, a minimum thickness of the adhesion layer 106 may befrom 0.8 μm to 3 μm, which should however not be construed as alimitation in the disclosure; in other embodiments, the thickness of theadhesion layer 106 may be increased by a printing build-up method.

With reference to FIG. 1C, the circuit layer 110 is formed by using the3D printing technology. The circuit layer 110 includes a conductivelayer 112 and a conductive bump 114. Specifically, the nozzle 212 of the3D printing apparatus is applied to eject a conductive ink 214 along thefirst direction D1 onto the adhesion layer 106 to form the conductivelayer 112 and eject the conductive ink 214 along the second direction D2onto the conductive layer 112 to form the conductive bump 114. In thiscase, as shown in FIG. 1C, the conductive layer 112 extends from the pad102 along the first direction D1 to cover a top surface 106 t of theadhesion layer 106. Particularly, the conductive layer 112 may include afirst portion 112 a, a second portion 112 b, and a third portion 112 c.The first portion 112 a covers and contacts the top surface 102 t of thepad 102. The second portion 112 b covers and contacts the top surface106 t of the adhesion layer 106. The third portion 112 c is locatedbetween the first portion 112 a and the second portion 112 b. That is,the third portion 112 c may be considered as a connecting portion or aninclined portion for connecting the first portion 112 a and the secondportion 112 b. Besides, the conductive bump 114 extends along the seconddirection D2 from the top surface 112 t of the conductive layer 112 onthe adhesion layer 106, wherein the top surface 112 t may be consideredas a first top surface. That is, the conductive bump 114 extends in anupward manner from the top surface 112 t in the second portion 112 b. Inan embodiment provided in the disclosure, the first direction D1 isdifferent from the second direction D2. Besides, the first direction D1is perpendicular to the second direction D2.

According to an embodiment, a minimum thickness of the conductive layer112 may be from 0.5 μm to 5 μm, and a minimum height of the conductivebump 114 is from 20 μm to 30 μm, which should however not be construedas a limitation in the disclosure; in other embodiments, the thicknessof the conductive layer 112 or the height of the conductive bump 114 canbe increased by a printing build-up method.

According to an embodiment, the conductive ink 214 includes a pluralityof conductive particles 115 and a solvent. The solvent includes NMP,PGME, ethylene glycol, or the like. To be specific, with reference tothe enlarged view 2 of a portion 108 of the circuit layer 110 of FIG.1C, after the curing step is performed, the circuit layer 110 (includingthe conductive layer 112 and the conductive bump 114) is constituted bya plurality of conductive particles 115 contacting each other. Accordingto an embodiment, the conductive particles 115 include a plurality ofmetal nanoparticles, e.g., silver nanoparticles, copper-silvernanoparticles, copper nanoparticles, or a combination thereof. Accordingto another embodiment, an average diameter of the conductive particles115 may be from 5 nm to 1000 nm. Standard deviation of particle diameterdistribution of the conductive particles 115 may be from 4.55 to 43. Insome embodiments, the circuit layer 110 is formed by the ball-shapedconductive particles 115 which are tightly connected, so as to achievethe effect of uniform electrical conductivity. In other embodiments, theconductive particles 115 may each have different diameters.

On the other hand, as shown in FIG. 2, the conductive layer 112 and theconductive bump 114 share one or more of the conductive particles 115.In other words, at least one of the conductive particles 115 crosses avirtual interface 113 between the conductive layer 112 and theconductive bump 114. Note that there is no actual interface between theconductive layer 112 and the conductive bump 114. The virtual interface113 herein is provided to clearly define that the conductive layer 112and the conductive bump 114 are integrally formed. The so-called“integrally formed” may be considered as being formed in the samemanufacturing process with use of the same material. For instance, theconductive layer 112 and the conductive bump 114 are formed by applyingthe same 3D printing technology with use of the same conductive ink 214.Since the conductive layer 112 and the conductive bump 114 areintegrally formed, the adhesion and IMC issues between differentmaterials can be prevented in the present embodiment. Thereby, thestructural strength between the conductive layer 112 and the conductivebump 114 can be significantly improved according to the presentembodiment, and product reliability can be further improved. That is tosay, the adhesion between the conductive layer 112 and the conductivebump 114 provided in the present embodiment is stronger than that of theconventional RDL structure, so that the conductive layer 112 and theconductive bump 114 are not easily peeled off or crack.

With reference to FIG. 1D, a passivation layer 116 is formed by usingthe 3D printing technology. Specifically, an insulation ink 224 isejected onto the conductive layer 112 along the first direction D1 by anozzle 222 of the 3D printing apparatus. According to an embodiment, theinsulation ink 224 includes an insulation material and a solvent. Theinsulation material includes polyimide, PU, or the like. The solventincludes NMP, PGME, ethylene glycol, or the like. After a curing step isperformed, the insulation ink 224 is cured and becomes the passivationlayer 116. In an alternative embodiment, the curing step includes aheating step or an irradiating step for volatilizing the solvent in theinsulation ink 224 and curing the insulation ink 224. In this case, asshown in FIG. 1D, the passivation layer 116 covers a top surface 112 t′of the conductive layer 112 which is not covered by the conductive bump114, and the passivation layer 116 covers a portion of a sidewall 114 sof the conductive bump 114. Here, the top surface 112 t′ may beconsidered as a second top surface. According to an embodiment, thepassivation layer 116 includes an insulation compound, such aspolyimide, an adhesive, or a combination thereof. In the presentembodiment, the passivation layer 116 may protect the conductive layer112 from oxygen or moisture. In another embodiment, a minimum thicknessof the passivation layer 116 can be from 0.7 μm to 4 μm, which shouldhowever not be construed as a limitation in the disclosure; in otherembodiments, the thickness of the passivation layer 116 may be increasedby a printing build-up method.

With reference to FIG. 1E, a solder layer 118 is formed by using the 3Dprinting technology. Specifically, a conductive ink 234 is ejected ontothe conductive bump 114 by a nozzle 232 of the 3D printing apparatus toform the solder layer 118. According to an embodiment, the conductiveink 234 includes conductive particles and a solvent. The conductiveparticles include a plurality of metal nanoparticles, e.g., silvernanoparticles, copper-silver nanoparticles, copper nanoparticles, or acombination thereof. The solvent includes NMP, PGME, ethylene glycol, orthe like. In another embodiment, a minimum thickness of the solder layer118 may be from 0.7 μm to 4 μm, which should however not be construed asa limitation in the disclosure; in other embodiments, the thickness ofthe solder layer 118 may be increased by stacking repeatedly. In analternative embodiment, the material of the solder layer 118 may be thesame as or different from the material of the circuit layer 110. Forinstance, the material of the circuit layer 110 includes a copper-silveralloy, and the material of the solder layer 118 includes a tin-silveralloy.

To sum up, the 3D printing technology is applied in the disclosure toform the circuit layer (including the conductive layer and theconductive bump), so that the conductive layer and the conductive bumpare integrally formed. Namely, the conductive layer and the conductivebump are made of the same material in the same manufacturing step, so asto prevent the adhesion and IMC issues between different materials.Thereby, the structural strength between the conductive layer and theconductive bump in the circuit structure can be significantly improvedaccording to one or more embodiments of the disclosure, and productreliability can be further improved. In addition, the method ofmanufacturing the circuit structure provided herein has simplemanufacturing steps, thus enhancing commercial competitiveness of theproduct.

Although exemplary embodiments of the disclosure have been described indetail above, the disclosure is not limited to specific embodiments, andvarious modifications and changes may be made within the scope of thedisclosure defined in the claims.

What is claimed is:
 1. A method of manufacturing a circuit structure,comprising: forming a pad on a substrate; forming a dielectric layer onthe substrate, wherein the dielectric layer has a first opening exposinga first portion of the pad; forming an adhesion layer on the dielectriclayer by using a first 3D printing technology, wherein the adhesionlayer covers a sidewall of the first opening and extends to cover a topsurface of the dielectric layer, thereby forming a second opening toexpose a second portion of the pad; and forming a circuit layer by usinga second 3D printing technology, wherein the forming the circuit layercomprises: forming a conductive layer, so that the conductive layercontacts the second portion of the pad and extends along a firstdirection from the pad to cover a top surface of the adhesion layer; andforming a conductive bump, so that the conductive bump extends along asecond direction from a first top surface of the conductive layer on theadhesion layer, wherein the first direction is different from the seconddirection, and the conductive layer and the conductive bump are formedin the same step of the second 3D printing technology.
 2. The method ofmanufacturing the circuit structure as recited in claim 1, wherein afterforming the conductive bump, the method further comprises forming apassivation layer by using a third 3D printing technology, so that thepassivation layer covers the second top surface of the conductive layerand laterally surrounds a portion of a sidewall of the conductive bump.3. The method of manufacturing the circuit structure as recited in claim1, wherein the forming the conductive layer comprises: forming a firsthorizontal portion on a bottom of the second opening to contact thesecond portion of the pad; forming an inclined portion along a sidewallof the second opening; and forming a second horizontal portion on thetop surface of the adhesion layer, wherein the second horizontal portionis higher than the first horizontal portion, the inclined portionconnects the first horizontal portion and the second horizontal portion,and the first horizontal portion, the second horizontal portion, and theinclined portion are integrally formed.
 4. The method of manufacturingthe circuit structure as recited in claim 3, wherein the conductivelayer does not fill up the second opening, so that a top surface of thefirst horizontal portion is lower than the top surface of the adhesionlayer.
 5. The method of manufacturing the circuit structure as recitedin claim 1, wherein an interface is free between the conductive layerand the conductive bump.
 6. The method of manufacturing the circuitstructure as recited in claim 1, wherein the conductive layer and theconductive bump are constituted by a plurality of conductive particlesin physical contact with each other, and a portion of the plurality ofconductive particles spans from the conductive layer to the conductivebump.
 7. The method of manufacturing the circuit structure as recited inclaim 6, wherein the plurality of conductive particles are ball-shapedconductive particles.
 8. The method of manufacturing the circuitstructure as recited in claim 1, wherein the forming the circuit layerby using the second 3D printing technology comprises using a conductiveink, the conductive ink comprises a plurality of metal nanoparticles,and the plurality of metal nanoparticles comprise silver nanoparticles,copper-silver nanoparticles, copper nanoparticles, or a combinationthereof.
 9. The method of manufacturing the circuit structure as recitedin claim 8, wherein the forming the adhesion layer by using a first 3Dprinting technology comprises using an insulation ink, the insulationink comprises polyimide, polyurethane, SU-8, an adhesive, or acombination thereof.
 10. The method of manufacturing the circuitstructure as recited in claim 1, further comprising forming a solderlayer on the conductive bump by using a fourth 3D printing technology.